But the initial investment I would not assume to be slight. Also, and I think (without any backup) that the many different "recipes" prevent the free market from working efficiently. When a shortage (due to whatever) occurs in a an area, it is difficult to supply the need from other shortages. Also it reduces competition if refineries specialize.
You are exactly right. What we need is standardization to prevent the "localized" fuel options. That plus fuel tax reductions and some regulatory relief would reduce pump prices fairly quickly.